Many authors (e.g. the late David Gordon), in particular when looking at the evidence post-1970s, argued that the American economy is profit-led. In other words, as profits (some emphasized profit shares while others prioritized profit rates; the profit rate time the level of capacity utilization gives the profit share) expanded, it stimulated investment, and this, in turn, led to output growth. Growth was driven by profits.
The idea is that, even though the reduction in wages has a negative effect on consumption and output growth, this is more than compensated by the increase in investment. However, there are some empirical problems (there are some theoretical issues that I’ll deal with in another post) with this kind of model (often referred to as Kaleckian, even though it seems that their origin should be traced to Joan Robinson’s Accumulation of Capital and the influential formalization by Bob Rowthorn in the early 1980s).
For starters, growth actually fell significantly after real wages stagnated. Also, the output-to-capital ratio (shown from 1960 to 2008 using a OECD measure), as can be seen in the graph below, does not indicate a marked shift in the 1970s. The output-to-capital ratio goes up in the Johnson and Clinton booms, and falls otherwise. The Reagan boom was mild at best. This is consistent with the accelerator. As the economy moves closer to full employment, the output-to-capital ratio, a proxy for capacity utilization, moves close to its maximum. The accelerator would suggest that investment adjusts capacity to output. Investment is not the locomotive of the system, is the rear car (the idea behind the accelerator principle).